Injection devices and methods for making and using them

ABSTRACT

Devices and methods are provided for delivering an agent into a patient&#39;s body using an injection device that includes a drive module and an injector module coupled to the drive module. The drive module includes a canister and puncture mechanism in a first chamber, a plunger in a second chamber communicating with the first chamber, and an actuator that moves the puncture mechanism to cause a puncture pin thereon to penetrate a septum of the canister and cause the gas within the canister to flow through the first chamber around the canister, and into the second chamber. The injector module includes a piston slidably disposed within an agent chamber and coupled to the distal end of the plunger such that, when the plunger moves from a retracted position to an extended position, the piston is advanced within the agent chamber to deliver an agent therein into a patient&#39;s body.

RELATED APPLICATION DATA

The present application claims benefit of co-pending U.S. provisionalapplications Ser. Nos. 62/581,701, filed Nov. 4, 2017, and 62/581,694,filed Nov. 4, 2017, the entire disclosures of which are expresslyincorporated by reference herein.

TECHNICAL FIELD

The present application relates generally to devices and methods fordelivering agents into a patient's body and, more particularly, toauto-injectors and/or gas-powered drive systems for injection devices,e.g., for delivering viscous agents into a patient's body, and tomethods for making and using such devices.

BACKGROUND

There are many applications involving delivery of a medicament or otheragent subcutaneously, intramuscularly, or otherwise into a patient'sbody. For example, auto-injectors are available that include apredetermined dose of the agent that may be delivered automatically intothe patient's body, e.g., after placement against the patient's skin andactivation. Generally, such auto-injectors are spring-loaded syringesthat are activated to release the spring, which generates sufficientforce to penetrate the skin with a needle and deliver the dose withinthe syringe. For viscous fluids, the forces required to develop fluidflow can be higher than spring-powered systems can provide. When springscan be used, they must generate a relatively high force that requiressprings of high mass. Consequently, such auto-injectors may makesubstantial noise, create pressure spikes in the syringe leading toglass breakage, vibrate, and/or may drive the needle forcefully into thepatient's skin, which may cause pain and/or may startle the user,particular when the patient is administering the injection themselves.Therefore, improved devices and methods for delivering agents into apatient's body would be useful.

SUMMARY

The present application is directed to devices and methods fordelivering agents into a patient's body and, more particularly, toauto-injectors and gas-powered drive systems for injection devices,e.g., for delivering viscous agents into a patient's body, and tomethods for making and/or using such devices.

In accordance with an exemplary embodiment, a device is provided fordelivering one or more agents into a patient's body that includes a) adrive module comprising an elongate drive housing including a first endand a second end, a first chamber adjacent the first end communicatingwith a second chamber adjacent the second end via an intermediatepassage; a puncture mechanism within the first chamber adjacent thefirst end including a puncture pin; a canister containing pressurizedgas including a penetrable septum disposed adjacent the puncture pin; anactuator configured to move one of the puncture mechanism and thecanister to cause the puncture pin to penetrate the septum and cause thegas within the canister to flow through the first chamber around thecanister, through the intermediate passage, and into the second chamber;and a plunger slidably disposed within the second chamber such that gasentering the second chamber causes the plunger to move from an initialposition to an extended position wherein a distal end of the plungerextends from the second end of the drive housing; and b) an injectormodule comprising an injector housing coupled to the drive housingcarrying an agent chamber containing one or more agents; a pistonslidably disposed within the agent chamber and coupled to the distal endof the plunger; and a needle extending from the injector module oppositethe drive housing and communicating with the agent chamber fordelivering the one or more agents from the agent chamber when theplunger moves from the retracted position to the extended position,thereby advancing the piston within the agent chamber.

In accordance with another embodiment, a device is provided fordelivering one or more agents into a patient's body that includes a) adrive module comprising an elongate drive housing including a first endand a second end, a first chamber adjacent the first end communicatingwith a second chamber adjacent the second end via an intermediatepassage; a puncture mechanism comprising a pin holder within the firstchamber immediately adjacent the first end including a puncture pin; acanister containing pressurized gas including a penetrable septumdisposed adjacent the puncture pin, the pin holder movable distally froman inactive position wherein the puncture pin is spaced away from theseptum and an active position wherein the puncture pin penetrates theseptum and causes the gas within the canister to flow through the firstchamber around the canister, through the intermediate passage, and intothe second chamber, the pin holder biased to the active position; one ormore catches on the drive housing adjacent the pin holder forrestraining the pin holder in the inactive position; an actuation sleeveslidably disposed over the drive housing and comprising a proximal enddisposed distal to the one or more catches; and a plunger slidablydisposed within the second chamber such that gas entering the secondchamber causes the plunger to move from an initial position to anextended position wherein a distal end of the plunger extends from thesecond end of the drive housing; and b) an injector module comprising aninjector housing coupled to the drive housing carrying an agent chambercontaining one or more agents; a piston slidably disposed within theagent chamber and coupled to the distal end of the plunger; a needleextending from the injector module opposite the drive housing andcommunicating with the agent chamber for delivering the one or moreagents from the agent chamber when the plunger moves from the retractedposition to the extended position, thereby advancing the piston withinthe agent chamber; and a needle guard movable from a guarded positionwherein the needle guard covers the needle and a retracted positionwherein the needle is exposed to perform an injection, the needle guardcoupled to the actuation sleeve such that proximal movement of theneedle guard towards the retracted position directs the actuation sleeveproximally to disengage the one or more catches, whereupon the pinholder automatically moves from the inactive position to the activeposition.

In accordance with still another embodiment, a drive module is providedfor an injection device for delivering one or more agents into apatient's body that includes an elongate drive housing including a firstend and a second end, a first chamber adjacent the first endcommunicating with a second chamber adjacent the second end via anintermediate passage; a puncture mechanism comprising a pin holderwithin the first chamber immediately adjacent the first end including apuncture pin; a canister containing pressurized gas including apenetrable septum disposed adjacent the puncture pin, the pin holdermovable distally from an inactive position wherein the puncture pin isspaced away from the septum and an active position wherein the puncturepin penetrates the septum and causes the gas within the canister to flowthrough the first chamber around the canister, through the intermediatepassage, and into the second chamber; a plunger slidably disposed withinthe second chamber such that gas entering the second chamber causes theplunger to move from an initial position to an extended position whereina distal end of the plunger extends from the second end of the drivehousing for delivering one or more agents from an injector module basedon movement of the plunger; and an actuator for directing the pin holderfrom the inactive position to active position.

In accordance with another embodiment, a method is provided forassembling an injector device that includes a) providing a drive modulecomprising an elongate drive housing including a first end and a secondend, a first chamber adjacent the first end communicating with a secondchamber adjacent the second end via an intermediate passage; a puncturemechanism comprising a pin holder within the first chamber immediatelyadjacent the first end including a puncture pin; a canister containingpressurized gas including a penetrable septum disposed adjacent thepuncture pin, the pin holder movable distally from an inactive positionwherein the puncture pin is spaced away from the septum and an activeposition wherein the puncture pin penetrates the septum and causes thegas within the canister to flow through the first chamber around thecanister, through the intermediate passage, and into the second chamber;a plunger slidably disposed within the second chamber such that gasentering the second chamber causes the plunger to move from an initialposition to an extended position wherein a distal end of the plungerextends from the second end of the drive housing for delivering one ormore agents from an injector module based on movement of the plunger;and an actuator for directing the pin holder from the inactive positionto active position; b) providing an injector module comprising aninjector housing carrying an agent chamber containing one or more agentsand a piston slidably disposed within the agent chamber in a proximalposition; and c) coupling the injector housing to the second end of thedrive housing, thereby coupling the plunger to the piston such when theplunger moves from the retracted position to the extended position, thepiston is advanced within the agent chamber to deliver the one or moreagents from the agent chamber.

In accordance with yet another embodiment, a method is provided forperforming an injection that includes a) providing an injection devicecomprising a drive module including a canister containing pressurizedgas within a first chamber and a plunger within a second chambercommunicating with the first chamber, and; an injector module includingone or more agents within an agent chamber, a piston within the agentchamber coupled to the plunger, and a needle extending from the injectormodule; b) inserting the needle through a patient's skin; and c)activating an actuator to cause a puncture pin within the drive moduleto penetrate a septum of the canister thereby causing gas within thecanister to flow through the first chamber around the canister and intothe second chamber, thereby moving the plunger from an initial positionto an extended position and, consequently, advancing the piston withinthe agent chamber to deliver the one or more agents through the needleinto the patient's body.

In accordance with still another embodiment, a method is provided forperforming an injection that includes a) providing an injection devicecomprising a drive module including a canister containing pressurizedgas within a first chamber and a plunger within a second chambercommunicating with the first chamber, and; an injector module includingone or more agents within an agent chamber, a piston within the agentchamber coupled to the plunger, a needle; and a needle guard coveringthe needle; b) pressing the needle guard against a patient's skin,thereby causing the needle guard to retract and inserting the needleinto the patient's skin; c) wherein retraction of the needle guardactivates an actuator to cause a puncture pin within the drive module topenetrate a septum of the canister thereby causing gas within thecanister to flow through the first chamber around the canister and intothe second chamber, thereby moving the plunger from an initial positionto an extended position and, consequently, advancing the piston withinthe agent chamber to deliver the one or more agents through the needleinto the patient's body.

In accordance with another embodiment, a device is provided fordelivering one or more agents into a patient's body that includes a) adrive module comprising an elongate drive housing including a first endand a second end, a first chamber adjacent the first end communicatingwith a second chamber adjacent the second end via an intermediatepassage; a puncture mechanism within the first chamber adjacent thefirst end including a puncture pin; a canister containing pressurizedgas including a penetrable septum disposed adjacent the puncture pin; anactuator configured to move the puncture mechanism distally to cause thepuncture pin to penetrate the septum and cause the gas within thecanister to flow through the first chamber around the canister, throughthe intermediate passage, and into the second chamber; and a plungerslidably disposed within the second chamber; and b) an injector modulecomprising an injector housing coupled to the drive housing carrying anagent chamber containing one or more agents; a piston slidably disposedwithin the agent chamber and coupled to a distal end of the plunger; anda needle extending from the injector module opposite the drive housing;and c) an outer sleeve surrounding the drive housing and the injectorhousing such that the drive housing and injector housing are slidablebetween a retracted position where the needle is withdrawn into a distalend of the outer sleeve and an advanced position where the needle isexposed from the distal end of the outer sleeve; the device configuredsuch that, when gas is initially released from the canister, the gaspressurizes the first chamber to cause the drive housing and injectorhousing to move to the advanced position to expose, and subsequentlypressurizes the second chamber to advance the plunger from a retractedposition to an extended position, thereby advancing the piston withinthe agent chamber to deliver the one or more agents from the agentchamber through the needle.

Other aspects and features of the present invention will become apparentfrom consideration of the following description taken in conjunctionwith the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is best understood from the following detailed descriptionwhen read in conjunction with the accompanying drawings. It isemphasized that, according to common practice, the various features ofthe drawings are not to-scale. On the contrary, the dimensions of thevarious features are arbitrarily expanded or reduced for clarity.Included in the drawings are the following figures.

FIG. 1 is a side view of an exemplary embodiment of an auto-injectordevice.

FIGS. 2A and 2B are cross-sectional views of the auto-injector device ofFIG. 1 taken along plane A-A and showing details of a gas-powered drivemodule and an injector module.

FIGS. 3A and 3B are cross-sectional views of an example of a gas-powereddrive module that may be included in the device of FIGS. 1-2B, showingthe drive module before and after activation, respectively.

FIG. 4A is a cross-sectional view of another example of a gas-powereddrive module including a two-section plunger.

FIG. 4B is a detail of the drive module of FIG. 4A after activationshowing forces acting on the plunger at different stages of advancement.

FIGS. 5A and 5B are cross-sectional views of yet another example of agas-powered drive module, showing the drive module before and afteractivation, respectively.

FIG. 5C is a detail of the drive module of FIGS. 5A and 5B, showing aflow path of gas released from the canister to advance a plunger.

FIGS. 6A and 6B are cross-sectional views of still another example of agas-powered drive module including a manual actuator for selectivelyactivating the drive module.

FIGS. 7A and 7B are cross-sectional views of another embodiment of agas-powered drive module that includes a plunger assembly providingdamping, showing the drive module before and after activation,respectively.

FIG. 8A is a side view of an exemplary plunger assembly that may beincluded in the drive module of FIGS. 7A and 7B.

FIG. 8B is a cross-sectional view of the plunger assembly of FIG. 8Ataken along plane 8B-8B.

FIG. 8C is a detail of a proximal plunger cap of the plunger assembly ofFIGS. 8A and 8B showing a removable plug for replacing an orifice withinthe plunger assembly.

FIG. 8D is a detail of a distal plunger cap of the plunger assembly ofFIGS. 8A and 8B showing distal ports.

FIGS. 9A and 9B are cross-sectional views showing examples of drivemodules including “in series” damping and “in parallel” damping,respectively.

FIGS. 10A and 10B are cross-sectional views of another example of agas-powered drive module, showing the drive module before and afteractivation, respectively.

FIGS. 11A-11E are cross-sectional views of another exemplary embodimentof an auto-injector device showing different stages of the injectordevice upon activation.

FIG. 11A(1) is a detail of a proximal end of the injector device ofFIGS. 11A-11E.

DETAILED DESCRIPTION OF THE EXEMPLARY EMBODIMENTS

The following detailed description is merely illustrative in nature andis not intended to limit the embodiments of the subject matter or theapplication and uses of such embodiments. As used herein, the word“exemplary” means “serving as an example, instance, or illustration.”Any implementation described herein as exemplary is not necessarily tobe construed as preferred or advantageous over other implementations.Furthermore, there is no intention to be bound by any expressed orimplied theory presented in the preceding technical field, background,brief summary, or the following detailed description.

Certain terminology may be used in the following description for thepurpose of reference only, and thus are not intended to be limiting. Forexample, terms such as “upper,” “lower,” “above,” and “below” refer todirections in the drawings to which reference is made. Terms such as“proximal,” “distal,” “front,” “back,” “rear,” and “side” describe theorientation and/or location of portions of the component within aconsistent but arbitrary frame of reference, which is made clear byreference to the text and the associated drawings describing thecomponent under discussion. Such terminology may include the wordsspecifically mentioned above, derivatives thereof, and words of similarimport.

For example, as used herein, the terms “front” and “distal” refer toparts of the subject device that are located further away from the user(e.g., clinician) of the device, e.g., during an injection operation. Asused herein, the terms “rear” and “proximal” refer to the parts of thedevice that are located closer to the user (e.g., clinician) of thedevice, e.g., during an injection operation.

Turning to FIGS. 1-3B, an exemplary embodiment of an injection device 8is shown that includes a gas-powered drive cartridge or module 10 and aninjector cartridge or module 60 coupled to the drive module 10, whichmay include components and/or perform similar to any of the embodimentsdescribed herein. Generally, the device 8 may be an auto-injector withthe drive module 10 providing force or power that, upon activation,automatically delivers one or more agents contained within the injectormodule 60, as described elsewhere herein. As used herein, “agent” mayinclude one or more therapeutic and/or diagnostic compounds ormaterials, e.g., in liquid or gaseous form, in solution or suspension,and the like, such as viscous fluids.

With particular reference to FIGS. 3A and 3B, the drive module 10includes an elongate drive housing 12 containing a puncture mechanism30, a gas canister 40, and a plunger 50. As shown, the drive housing 12includes an enclosed first or proximal end 14 and an open second ordistal end 16 aligned along a longitudinal axis 18 of the device 8. Thehousing 12 may be formed as a single, integral component, e.g., frommetal, such as steel, aluminum, and the like, plastic, and/or compositematerial, by one or more of cold drawing, molding, casting, machining,and the like. Alternatively, the housing 12 may be formed from multiple,separate components that are substantially permanently attachedtogether, e.g., by one or more of welding, soldering, fusing, bondingwith adhesive, interference fit, and the like.

As shown, the drive housing 12 includes a first or proximal portion 20adjacent the first end 14 defining a first chamber 22 and a second ordistal portion 24 adjacent the second end 16 defining a second chamber26 communicating with the first chamber 22 via an intermediate passage28. Both housing portions 20, 24 may have a generally cylindrical shape,e.g., defining a substantially uniform outer and/or inner diameter, withthe proximal portion 20 having a larger outer diameter or othercross-section than the distal portion 24.

The puncture mechanism 30 may be provided within the first chamber 22immediately adjacent the first end 14 and the canister 40 containingcompressed gas may be disposed within the first chamber 22 adjacent thepuncture mechanism 30. The plunger 50 may be an elongate rod or othermember slidably disposed within the second chamber 26 such that theplunger 50 that is movable from an initial position (e.g., shown in FIG.3A) to an extended position (e.g., shown in FIG. 3B) wherein a distalend 54 of the plunger 50 extends from the second end 16 of the drivehousing 12, as described further elsewhere herein. Optionally, a plungerstop 57 may be provided on the distal end 16 of the drive housing 12,e.g., to guide the plunger 50 during advancement and/or to limit distalmovement in the extended position, e.g., when the proximal end 52 of theplunger 50 abuts the stop 57.

Generally, with particular reference to FIGS. 3A and 3B, the canister 40includes a body 42 and a cap 44 including a septum 46 welded to the body42 to provide an enclosed cavity 48 filled with a fluid containingliquefied gas, such as carbon dioxide or fluorocarbon gases, compressedto sufficient pressure to least partially liquefy the gas within thecavity 48. Alternatively, fluids containing gases such as argon,nitrogen, helium argon, or other combinations thereof that remain ingaseous form may be stored within the cavity 48. As described elsewhereherein, the fluid contained within the cavity 48 may be used to providea desired potential energy or discharge force to drive the injectiondevice 8, e.g., to inject one or more agents from the injector module 60into a patient's body. In an exemplary embodiment, the body 42 and cap44 may be formed from stainless steel or other desired or suitablemetal, plastic, or composite material, e.g., formed by one or more ofdrawing, stamping, machining, casting, molding, and the like. Forexample, the body 42 may be deep drawn from sheet metal, e.g., a roundsheet metal blank of Type 305 stainless steel, using one or more diesand punches (not shown), to form a main barrel region 42 a, an enclosedbase or first end 42 b, a tapered shoulder region 42 c, and an open neckregion or second end 42 d defining an opening or passage within whichthe cap 44 is attached. Additional information regarding canisters thatmay be used and methods for making them may be found in U.S. PublicationNo. 2017/0258583, the entire disclosure of which is expresslyincorporated by reference herein.

In the embodiment shown in FIGS. 3A and 3B, the puncture mechanism 30includes a pin sleeve 32 slidably disposed within the first chamber 22adjacent the first end 14, i.e., between the second end 42 d and cap 44of the canister 40 and a proximal wall 14 a enclosing the first chamber22. The pin sleeve 32 carries a puncture pin 34 and is movable withinthe first chamber 22, e.g., axially between an inactive position whereinthe puncture pin 34 is spaced apart from the septum 46 (FIG. 3A) and anactive position wherein the puncture pin 34 penetrates the septum 46(FIG. 3B) to release gas from the cavity 48 of the canister 40, asdescribed elsewhere herein.

The pin sleeve 32 may be biased to the active position and restrained inthe inactive position, e.g., by one or more catches 36 on the drivehousing 12 restraining the pin sleeve 32 in the inactive position. Forexample, a compression spring 38 may be disposed around the pin sleeve32 and/or otherwise coupled between the housing 12 and the pin sleeve 32to direct the pin sleeve 32 from the inactive position to the activeposition when activated.

For example, as shown in FIGS. 3A and 3B, the spring 38 may beconstrained between a distal flange 32 a on the pin sleeve 32 and theproximal wall 14 a of the drive housing 12. A pair of catches 36 may bemounted to the drive housing 12 that are pivotable from an outwardorientation (FIG. 3A), where the catches 36 contact the distal flange 32a to prevent movement of the pin sleeve 32 from the inactive position,to an inward position (not shown), where the catches 36 release thedistal flange 32 a and allow the spring 38 to direct the pin sleeve 32distally to the active position, e.g., sufficient distance such that thepuncture pin 34 penetrates the septum 46 of the canister 40.

When the septum 46 is penetrated, gas within the cavity 48 is releasedinto the first chamber 22, e.g., such that the gas travels distallyaround the canister 40, through the intermediate passage 28, and intothe second chamber 26. For example, the drive housing 12 and canisterbody 42 may have corresponding diameters to provide sufficient clearanceto allow the gas to travel distally around the canister 40 within thefirst chamber 22 and enter the intermediate passage 28, as describedelsewhere herein (e.g., as shown in FIG. 5C).

Optionally, the intermediate passage 28 may have a relatively smalldiameter to provide a restrictor to reduce the pressure rise time.Alternatively, a precision orifice (not shown) may be inserted betweenthe first and second chambers 22, 26, if desired to act as a restrictor.For example, an orifice may i) slow down the transient flow of gas,slowing the rise of pressure imparted to the plunger 50, e.g., providinga soft-start to the injection, reducing/eliminating pressure shock wavesin the fluid to be injected in the syringe and possibly reducing patientpain as the drug injection is gently initiated; and/or ii) slow down thesteady state flow of gas, reducing the otherwise pressure imparted tothe plunger 50, providing a limiting effect to the flow rate of the druginjected into the patient.

In an exemplary embodiment, the drive housing 12 may be shaped such thatthe first chamber 22 has a shape similar to the canister body 42 butslightly larger in diameter to provide the clearance to allow gas flow.For example, the drive housing 12 may be sized and shaped to minimizedead space around the canister 40, i.e., to preserve gas pressure andmaximize transfer of gas pressure through the intermediate passage 28into the second chamber 26. In an exemplary embodiment, it may bedesirable to have the dead space around the canister 40 be not more thanabout five percent (5%) of the volume of the cavity 48 of the canister40 to ensure proper transfer of the pressure to the plunger 50. Forexample, in order to maintain a constant vapor pressure when thecanister 40 is filled with a dual phase gas, the volume the gas fillswhen it is released must be less than the “expanded volume” of the gasto have residual liquid phase of gas present. As long as liquid phase ofgas remains, the pressure is constant and equal to the vapor pressure ofthe gas.

Gas entering the second chamber 26 causes the plunger 50 to move fromthe initial position (FIG. 2A) to the extended position (FIG. 2B),thereby directing the distal end 52 of the plunger 50 axially anddistally from the open second end 16 of the drive housing 12. Forexample, as shown, a proximal end 52 of the plunger 50 may include oneor more O-rings and/or other seals 53 to prevent the gas from escapingaround the proximal end 54, thereby applying a predetermined distalforce to the proximal end 52 corresponding to the pressure of the gasand the surface area of the proximal end 52 to direct the plunger 50 tothe extended position. As described elsewhere herein, the gas may applya substantially uniform and/or constant force against the proximal end52 to drive an injector device 60 coupled to the drive module 10, e.g.,as long as at least some of the gas within the cavity 48 remainsliquefied after release.

Returning to FIGS. 1-2B, the injector 60 generally includes an injectorhousing 62 coupled to the drive housing 12 and carrying a syringe 70therein including an agent chamber 72 containing one or more medicamentsor other agents. For example, the injector housing 62 may include afirst or proximal end 62 a that may be coupled to the drive housing 12,e.g., using one or more of an interference fit, one or more cooperatingconnectors, bonding with adhesive, and the like, e.g., to an outersleeve 66 within which at least a portion of the drive housing 12 may besecured, and a second or distal end 62 b opposite the drive housing 12.In an exemplary embodiment, the proximal end 62 a of the injectorhousing 62 communicates with an interior 64 of the injector housing 62and the distal end 62 b is at least partially enclosed.

Generally, the syringe 70 includes a barrel 74 and a piston or stopper76 slidably disposed therein to enclose the agent chamber 72. A needle78 may extend from a closed distal end 74 a of the barrel 74. In anexemplary embodiment, the syringe 70 may be a pre-filled syringe, e.g.,formed from glass, plastic, and the like, filled with a predeterminedvolume of agent, e.g., corresponding to a single dose for a patient. Theagent chamber 72 may include one or more therapeutic and/or diagnosticagents, e.g., a viscous fluid having a viscosity greater than water,e.g., between about one and two thousand centipoise (1.0-2000 cP), e.g.,including large proteins and/or other medicaments that requiresubstantial force and/or time to deliver.

Optionally, one or more flanges or other features 75 may be provided ona proximal end 74 b of the barrel 74 that may engage one or moredetents, ridges, or other features (not shown) within the injectorhousing 62. For example, during manufacturing or assembly, a syringe 70may be selected that may be inserted into the interior 64 through theproximal end 62 a of the injector housing 62, e.g., until the needle 78extends partially through the distal end 62 b and the flange 75 on thesyringe 70 is captured by the feature(s) on the injector housing 62. Theproximal end 62 a of the injector housing 62 may then be coupled to theouter sleeve 66 of the drive module 10 to encapsulate the components andprovide the injector device 8 ready for use.

Alternatively, the injector module 60 may include an integral barrel(not shown) defining the agent chamber 72 and carrying the needle 78.For example, the injector housing 62 may define a substantially enclosedagent chamber (not shown) that slidably receives the piston 76 andincludes a needle 78 permanently mounted to the injector housing 62 fordelivering the agent within the agent chamber 72. In a furtheralternative, the syringe 70 (or injector housing 62 with integral agentchamber) may include a distal port (not shown) without a needle, suchthat a separate needle (also not shown) may be coupled to the port,e.g., using a Luer fitting, mating threads, and/or other cooperatingconnectors, immediately before an injection or otherwise as desired.

The piston 76 may be coupled to the distal end 54 of the plunger 50,e.g., during assembly of the injector housing 62 to the outer sleeve 66,such that subsequent advancement of the plunger 50 causes the piston 76to advance within the agent chamber 72 to direct the one or more agentsthrough the needle 78 into a patient's body, e.g., automatically uponactivation of the puncture mechanism 30, as described further elsewhereherein. Optionally, a plunger adapter 58 may be provided that mayprovide an interface between the distal end 54 of the plunger 50 and thepiston 76, e.g., to provide connectors therebetween and/or ensure properspacing such that the piston 76 is advanced in conjunction with theplunger 50.

In addition, as best seen in FIGS. 3A and 3B, a needle guard 80 may beslidably mounted to the injector housing 62 that is movable from aguarded position wherein the needle guard 80 covers the needle 80 (shownin FIGS. 3A and 3B) to a retracted position wherein the needle 78 isexposed to perform an injection (not shown). The needle guard 80 may becoupled to the catches 36, e.g., such that retraction of the needleguard 80 to expose the needle 78, e.g., during an injection, causes thecatches 36 to release the puncture mechanism 30, thereby triggering thepuncture pin 34 penetrating the septum 46, releasing the gas within thecanister 40, and automatically advancing the plunger 50 and piston 76 todeliver the one or more agents through the needle 78 into the patient'sbody.

For example, the needle guard 80 may include a proximal or first end 80a disposed around or adjacent the drive housing 12 and a distal orsecond end 80 b disposed distally beyond the needle 78 in the guardedposition. In the exemplary embodiment shown, the distal end 80 bincludes a closed wall having a relatively small opening therethrough toaccommodate exposure of the needle 78 when the needle guard 80 isretracted.

An actuation sleeve 84 may be slidably disposed over the drive housing12, e.g., within the outer sleeve 66, that is coupled to the needleguard 90 such that axial movement of the needle guard 80 causescorresponding movement of the actuation sleeve 84 (and vice versa). Inthe embodiment shown, the actuation sleeve 84 includes a proximal orfirst end 84 a including one or more ramped surfaces or other featuresfor interacting with the catches 36 and a distal or second end 84 bdisposed adjacent and/or contacting the proximal end 80 a of the needleguard 80.

A spring mechanism 82 may be provided that biases the needle guard 80 tothe guarded position but allows the needle guard 80 to be retracted toexpose the needle 78, e.g., when the needle guard 80 is pressed againsta patient's skin at an intended injection site. For example, acompression spring 82 may be disposed around the drive housing 12, e.g.,surrounding a length of the distal portion 24, which is surrounded, inturn, by the actuation sleeve 84. The distal end 84 b of the actuationsleeve 84 may include one or more flanges or other features that engagethe spring 82 such that proximal movement of the needle guard 80 fromthe guarded position pushes the distal end 84 a of the actuation sleeve84, thereby compressing the spring 82 as the actuation sleeve 84 movesproximally. Subsequently, when the needle guard 80 is released, e.g.,after an injection, the spring 82 may automatically direct the actuationsleeve 84 distally, thereby returning the needle guard 80 back to theguarded position.

When the needle guard 80 is in the guarded position, the proximal end 84a of the actuation sleeve 84 may be spaced apart distally from thecatches by a desired distance distally from the catches 36. For example,the distance may correspond to the length of the needle 78 and/ordesired displacement distance for the needle guard 80 such that theproximal end 84 a engages the catches 36, e.g., to direct them to theinward position or otherwise releasing the pin sleeve 30 when the needleguard 80 is directed towards the retracted position, e.g., before orafter full retraction of the needle guard 80.

In the embodiment shown in FIGS. 2A and 2B, the proximal end 84 a of theactuation sleeve 84 may include a ramped or beveled edge that mayslidably engage the outwardly oriented catches 36. Thus, when theactuation sleeve 84 moves proximally, e.g., when the distal end 80 b ofthe needle guard 80 is pressed against a patient's skin for aninjection, the proximal edge 84 a of the actuation sleeve 84 may pushthe catches 36 inwardly until the pin sleeve 30 is released. Uponcompletion of an injection, the device 8 may be withdrawn away from thepatient's skin, whereupon the actuation sleeve 84 may resiliently returndistally, thereby directing the needle guard 80 back to the guardedposition, e.g., to facilitate disposal of the device 8 and/or otherwiseminimize the risk of accidental needle sticks.

The injector housing 62, outer sleeve 66, needle guard 80, actuationsleeve 84, and plunger adapter 58 may be formed from conventionalmaterials, e.g., plastic, metal, composite materials, and the like,e.g., to provide a rigid and/or relatively lightweight injector device 8that may be used by a patient themselves and/or by an untrained user.Optionally, the outer sleeve 66 may be ergonomically shaped, e.g., tofacilitate manipulation by the user, e.g., including one or more gripelements (not shown) to minimize risk of the device 8 slipping duringuse.

Optionally, the injector module 60 may include one or more additionalfeatures to facilitate use. For example, as shown in FIG. 1, theinjector housing 62 may include one or more windows 68 to allow the userto observe the syringe 70, agent chamber 72, and/or piston 76, e.g., tovisually monitor advancement of the piston 76 and delivery of the agenttherein. In addition or alternatively, a cap 69 may be provided that maybe removably coupled to the distal end 62 b of the injector housing 62,e.g., to prevent premature movement of the needle guard 80 and/or otheraccidental activation of the device 8. For example, the cap 69 maysimply slide over the distal end 62 b, e.g., held by interference fit,and/or the cap 69 and distal end 62 b may include cooperating detents orother features to secure the cap 69 yet allow removal immediately beforean injection.

It will be appreciated that the relative dimensions of the injectormodule 60 and drive module 10 may be selected to provide a desiredinjection configuration. For example, for viscous agents, it may bedesired to set the cross-sectional area of the proximal end 54 of theplunger 50 to provide a desired force on the plunger 50 to advance thepiston 76 at a desired speed to achieve full displacement and/orcomplete delivery of the agent in a predetermined elapsed time, e.g.,between about fifty milliseconds and thirty seconds (50 msec.-30 sec.),or within about five seconds. In an exemplary embodiment, the dimensionsof the device 8 may be set such that, upon retraction of the needleguard 80, e.g., upon being pressed against a patient's skin to insertthe needle 78 through the skin, the needle guard 80 and actuation sleeve84 may immediately release the catches 36, thereby releasing the pinsleeve 32 to cause the puncture pin 34 to penetrate the septum 46 andrelease the gas from the canister 40 without providing any unexpectedmovement and/or sounds to the user. The gas may then flow distallyaround the canister 40 within the first chamber 22, through theintermediate passage 28 and into the second chamber 26, thereby applyinga predetermined force to the plunger 50 (based on the pressure of thegas, the flow restriction of intermediate passage 28, and the surfacearea of the proximal end 54 of the piston). These parameters may beselected to provide a force to overcome the viscosity of the agentwithin the syringe 70 and cause the piston 76 to advance at a desiredspeed to complete the injection in a desired time.

Upon completing the injection, the user may simply withdraw the device 8away from the patient's skin to withdraw the needle 78, thereby allowingthe needle guard 80 to advance back to the guarded position andfacilitate disposal of the device 8. Optionally, the cap 69 may bereplaced over the needle guard 80 to prevent accidental sticks beforedisposal. Alternatively, the needle guard may include a lockingmechanism (not shown) that may be locked, such as by rotating the needleguard 80, e.g., a quarter turn, or otherwise engaged to preventsubsequent retraction of the needle guard 80.

The components of the injector device 8 may be assembled together duringmanufacturing, during preparation by a pharmacist or other intermediary,or by the user themselves immediately before performing an injection.For example, in one method, the drive module 10 may be fabricated andassembled during manufacturing to provide the drive housing 12containing the pin mechanism 30, canister 40, and plunger 50 in theinitial configuration shown in FIG. 3A. In this manner, the drive module10 may provide a standard power source that may be selected for a giveninjector module 60. In addition or alternatively, the outer sleeve 66,actuation sleeve 84 and/or spring mechanism 82 may be preassembledaround the drive housing 12 to provide a complete drive module 10 thatmay be quickly assembled to an injector module 60.

Optionally, as described above, multiple drive modules 10 may beprovided having different configurations, e.g., gas pressures and/orpiston sizes, to allow a desired force pattern to be selected when aninjection device 8 is being assembled. Similarly, the components of theinjector module 60, as well as the outer sleeve 66, actuation sleeve 84,and/or plunger adapter 58 may be manufactured in various configurationsand/or sizes, e.g., to accommodate different size syringes 70 and/orprovide desired activation timing.

Individual injection devices 8 may be assembled during initialmanufacturing by selecting a desired syringe 70, inserting the syringe70 into an injector housing 62, e.g., until the syringe 70 is securedtherein, and coupling the resulting injector module 60 to a selecteddrive module 10 to provide a complete device 8, which may be sterilized,packaged, and/or otherwise processed before being sent to distributorsand/or users. Alternatively, the components, e.g., drive modules 10 andinjector modules 60, may be shipped separately to a pharmacy or otherlocation, where an intermediate user may select syringes, drive modules10, and/or other combinations of components, and complete assemblybefore the devices 8 are provided to end users. In a furtheralternative, the components may be provided to the end user, who maycomplete assembly, e.g., immediately before performing an injection.

Turning to FIGS. 4A and 4B, in some applications, it may be desirable toprovide an injector device that changes the force, and thus the speed ofthe piston during different stages of advancement after activation. Forexample, FIG. 4A shows another embodiment of a drive module 110 that maybe provided within an injection device, e.g., in place of the drivemodule 10 shown in FIGS. 2A and 2B. Similar to the previous embodiment,the drive module includes a drive housing 112 including a first portion20 defining a first chamber 22 containing a puncture mechanism 30 and agas canister 40. The puncture mechanism 30 may include a pin sleeve 32provided within the first chamber 22 immediately adjacent a first end114 of the drive housing 112 and the canister 40 may be disposed withinthe first chamber 22 distal to the puncture mechanism 30, e.g., with theseptum 46 oriented proximally towards a puncture pin 34 carried by thepin sleeve 32.

The pin sleeve 32 is movable within the first chamber 22, e.g., axiallyfrom an inactive position wherein the puncture pin 34 is spaced apartfrom the septum 46 and an active position wherein the puncture pin 34penetrates the septum 46 to release gas from the cavity 48 of thecanister 40, as described elsewhere herein. The pin sleeve 32 may bebiased to the active position and restrained in the inactive position,e.g., by one or more catches 36 on the drive housing 112 restraining thepin sleeve 32 in the inactive position. For example, similar to theprevious embodiment, a compression spring 38 may be disposed around thepin sleeve 32 and/or otherwise coupled between the drive housing 112 andthe pin sleeve 32 to direct the pin sleeve 32 from the inactive positionto the active position when activated.

Unlike the previous embodiment, the drive housing 112 includes a secondportion 124 including first and second plunger chambers 126 a, 126 b anda plunger 150 including first and second portions 150 a, 150 b. Asshown, the first plunger chamber 126 a and first portion 150 a have adiameter or other cross-section that is smaller than the second plungerchamber 126 b and second portion 150 b. In an initial position, thefirst portion 150 a of the plunger 150 is disposed within the firstplunger chamber 126 a, e.g., such that a proximal end 152 a of the firstportion 150 a is disposed immediate adjacent the intermediate passage(not shown) communicating with the first chamber 22. Similarly, thesecond portion 152 b of the plunger 150 is disposed within the secondplunger chamber 126 b, e.g., such that a proximal end 152 b of thesecond portion is disposed immediately adjacent the end of the firstplunger chamber 126 a.

In this manner, when the catches 36 are disengaged to release thepuncture mechanism 30 and the puncture pin 34 penetrates the septum 46,gas from the cavity 48 may flow from the canister 40 through the firstchamber 22 distally around the canister 40 until the gas enters thefirst plunger chamber 126 a. Because the pressure from the gas is actingon the relatively small surface area of the first portion 150 a of theplunger 150, a relatively small drive force (F1) is applied, which maycause the plunger 150 (and a piston, not shown, coupled to the distalend 154) to advance at a relatively slow initial speed. Once theproximal end 152 a of the first portion 150 a enters the second plungerchamber 126 b, the pressure from the gas may be applied to theadditional surface area of the second portion 152 b of the piston 150,thereby applying an additional drive force (F2), which may increase thespeed at which the plunger 150 (and piston) are advanced for theremainder of an injection.

The length of the first plunger chamber 126 a and first portion 150 a ofthe plunger 150 may be selected to cause the plunger 150 to advance atthe relatively slow speed for a predetermined time and/or distancebefore increasing to the second speed. For example, as described inother embodiments herein, an auto-injector may automatically advance aneedle to penetrate the patient's skin and then deliver the one or moreagents. In such embodiments, the length of the first plunger chamber 126a and/or first portion 150 a may be set to correspond to penetration ofthe needle to a desired depth, e.g., such that the needle is insertedinto the patient's skin at a relatively slow speed, which may minimizediscomfort and/or surprise, whereupon the plunger may then beaccelerated to the higher speed to complete injection of the agent(s)relatively quickly.

Turning to FIGS. 5A and 5B, yet another embodiment of a drive module 210is shown that may be provided within an injection device, e.g., in placeof the drive module shown in FIGS. 2A and 2B. Similar to otherembodiments herein, the drive module 210 includes a drive housing 212includes a first portion 220 defining a first chamber 222 containing apuncture mechanism 230 and a gas canister 40, and a second portion 224defining a second chamber 226 communicating with the first chamber 222via an intermediate passage 228. A plunger 50 is slidably receivedwithin the second chamber 226 such that the plunger 50 is movable froman initial position (e.g., shown in FIG. 5A) to an extended position(e.g., shown in FIG. 5B) wherein a distal end 54 of the plunger 50extends from the second end 216 of the drive housing 212. Optionally,similar to other embodiments, a plunger stop 57 may be provided on thedistal end 216 of the drive housing 212, e.g., to guide the plunger 50during advancement and/or limit distal movement, e.g., when a proximalend 52 of the plunger 50 abuts the stop 57.

In this embodiment, the puncture mechanism 230 includes a lead screw orother body 232 movably received through the first end 214 of the drivehousing 212 and carrying a puncture pin 234. The canister 40 is providedwithin the first chamber 222 distal to the puncture mechanism 230, e.g.,with the septum 46 oriented proximally towards a puncture pin 234. Thecanister 40 may be fixed relative to the drive housing 212, e.g., bycooperating threads on the outer surface of the neck or barrel of thecanister 40 and on the inner surface of the drive housing 212.Alternatively, the canister 40 may be secured using a hem feature (notshown). Similar to other embodiments, the drive housing 212 may beshaped such that the first chamber 222 has a shape similar to thecanister 40 but slightly larger in diameter to provide the clearance toallow gas flow, e.g., sized and shaped to minimize dead space around thecanister 40, i.e., to preserve gas pressure and maximize transfer of gaspressure through the intermediate passage 228 into the second chamber226.

The lead screw 232 and corresponding opening in the first end 214 mayinclude cooperating threads such that rotation of the lead screw 232causes the lead screw 232 to advance from the inactive position shown inFIG. 5A, where the puncture pin 234 is spaced from the cap 44 of thecanister 40, to the active position shown in FIG. 5B, where the puncturepin 234 penetrates the septum 46 to release gas contained within thecavity 48 of the canister 40. An outer end of lead screw 232 (outsidethe drive housing 212) may include a connector that may be coupled to atool or other actuator (not shown) to cause rotation of the lead screw232. For example, a dial, handle, or other actuator may be mounted on anouter sleeve (not shown) surrounding the drive housing 212 (e.g., on aproximal end of a sleeve similar to the outer sleeve 66 shown in FIG. 1)to allow a user to rotate the actuator and cause the puncture pin 234 toadvance distally until the septum 46 is penetrated.

Similar to other embodiments, as shown in FIG. 5C, once the septum 46 ispenetrated, gas may travel from the cavity 48 through the first chamber222 distally around the canister 40, through the intermediate passage228 into the second chamber 226, thereby advancing the plunger 50distally. The plunger 50 may, in turn, be coupled to a piston of asyringe or other component of an injector module (not shown) to deliverone or more agents from the injector module into a patient's body.

It will be appreciated that for vapor-only gases within the canister 40,the larger the dead volume within the drive housing 212, the lower theresulting pressure delivered to the plunger 50. When liquefied gas isprovided within the canister 40, the expansion volume determines whenthe liquid phase of the gas is converted to vapor phase. As long as aportion of liquefied gas remains, the pressure applied to the plunger 50will be substantially constant. For example, for a canister containing0.7 mL of liquefied gas, constant pressure may be maintained, e.g.,until 1.5 mL of total gas volume or other correct volume of dual-phasegas is reached. Region “R” identified in FIG. 5C may provide a pocketfor containing a resistance element (not shown) to potentially dampen orthrottle flow of gas through the intermediate passage 228 into thesecond chamber 226. In exemplary embodiments, the resistance element mayinclude permeable material, such as silicone, a graphite plug, filtermedia, and the like. Alternatively, an orifice may be used as theresistance element. Such resistance elements may be provided in any ofthe drive modules described herein.

In other embodiments, manual actuators may be provided for causing apuncture pin to penetrate the septum of the canister and/or release gasfrom the canister. For example, turning to FIGS. 6A and 6B, anotherexample of a drive module 310 is shown that generally includes a drivehousing 312 containing a puncture mechanism 330, a canister 40, and aplunger 350, generally similar to other embodiments herein.

For example, the drive housing 312 generally includes a first portion320 defining a first chamber 322 containing the puncture mechanism 330and gas canister 40, and a second portion 324 defining a second chamber326 communicating with the first chamber 322 via an intermediate passage328. The plunger 350 is slidably received within the second chamber 326such that the plunger 350 is movable from an initial position (FIG. 6A)to an extended position (FIG. 6B) wherein a distal end (not shown) ofthe plunger 350 extends from a second end (also not shown) of the drivehousing 312.

However, in this embodiment, the puncture mechanism 330 includes a pinholder or base 332 carrying a puncture pin 334 that is slidable axiallywithin the drive housing 312, e.g., between an inactive position shownin FIG. 6A, where the puncture pin 334 is spaced from the cap 44 of thecanister 40, and the active position shown in FIG. 6B, where thepuncture pin 334 penetrates the septum 46 to release gas containedwithin the cavity 48 of the canister 40.

In addition, the drive module 310 includes a toggle actuator 338 coupledto the pin holder 332 to direct the pin holder 332 between the inactiveand active positions. As shown, the actuator 338 includes a handle 338 apivotable relative to the drive housing 312 about pivot 338 c, and alinking bar 338 b coupled between the handle 338 a and the pin holder332.

Before activation, i.e., with the pin holder 332 in the inactiveposition, the handle 338 a may extend at an acute angle relative to thelongitudinal axis 318, as shown in FIG. 6A. When the user presses thehandle 338 a down against the drive housing 312, e.g., substantiallyparallel to the longitudinal axis 318, as shown in FIG. 6B, the handle338 a rotates about the pivot 338 c, generating an amplified forcethrough the linking bar 338 b, which is translated to linear slidingmotion of the pin holder 332. As the pin holder 332 advances distally,the septum 46 may be penetrated with minimal effort, thereby releasingthe gas, which may then travel distally through the first chamber 322around the canister 40 into the second chamber 326, thereby advancingthe plunger 350, similar to other embodiments herein. In addition, afterrelease of the gas, pressure from the gas may direct the pin holder 332proximally, thereby directing the handle 338 a back out to its initialposition shown in FIG. 6A.

In some applications, it may be desirable to provide damping within adrive module, e.g., using damping oil, such as silicone, and/or otherincompressible and/or viscous fluids. For example, turning to FIGS. 7Aand 7B, another example of a drive module 410 is shown that generallyincludes a drive housing 412 containing a puncture mechanism 430, acanister 40, and a plunger 450, generally similar to other embodimentsherein. For example, the drive housing 412 includes a first portion oractuation housing 420 defining a first chamber 422 containing thepuncture mechanism 430 and gas canister 40, and a second portion orcylinder 424 defining a second chamber 426 communicating with the firstchamber 422.

In this embodiment, the puncture mechanism 430 includes a pin holder orbase 432 carrying a puncture pin 434 that is slidable axially within thedrive housing 412, e.g., between an inactive position shown in FIG. 7A,where the puncture pin 434 is spaced from the cap 44 of the canister 40,to an active position shown in FIG. 7B, where the puncture pin 434penetrates the septum 46 to release gas contained within the cavity 48of the canister 40 and advance the plunger 450, similar to otherembodiments herein. In addition, a button or other actuator 438 extendsfrom the first end 414 of the drive housing 412 that is coupled to thepin holder 432, e.g., such that the actuator 438 may be pressed orotherwise manually activated to direct the puncture pin 434 distally topenetrate the septum 46.

The plunger 450 is slidably received within the second chamber 426 suchthat the plunger 450 is movable from an initial position (FIG. 7A) to anextended position (FIG. 7B) wherein a distal end 452 b of the plunger450 extends from a second end 416 of the drive housing 412. In addition,unlike previous embodiments, damping fluid 459 may be provided withinthe second chamber 426, e.g., substantially filling the annular spacearound the plunger 450.

As best seen in FIGS. 8A and 8B, the plunger 450 includes a tubular body452 including a first or proximal end 452 a and a second or distal end452 b and defining an internal chamber 454 extending therebetween thatis initially empty, e.g., before performing an injection. The plunger450 may also include a distal plunger cap 460 on the distal end 452 band a proximal plunger cap 462 on the proximal end 452 a to encloseand/or isolate internal chamber 454, while allowing the damping fluid459 within the second chamber 426 to flow into the internal chamber 454during advancement of the plunger 450. For example, one or more proximalports 466 (one shown in FIG. 8A) may be provided on the proximal end 452a that communicate with an orifice 458 mounted within the proximal end452 a of the plunger 450, e.g., to provide a path for the damping fluidto flow from the second chamber 426 into the internal chamber 454, e.g.,as shown by the arrows in FIG. 8B.

In addition, an internal piston 456 is disposed within the internalchamber 454, e.g., initially in a proximal position shown in FIG. 7A,that is slidable distally to a distal position shown in FIG. 7B, e.g.,as damping fluid 459 enters the internal chamber 454 through the orifice458. Optionally, one or more O-rings may be provided, e.g., O-ring 462 aon the proximal plunger plug 462, O-ring 456 a on the internal piston456, and the like, to provide a fluid-tight seal to prevent the dampingoil from escaping (other than traveling through the orifice 458 from theannular space within the second chamber 426 into the internal chamber454).

During operation, the puncture mechanism 430 may be activated, e.g. bymanually depressing the button 438, causing the puncture pin 434 topenetrate the septum 46 and release the gas, which may then flowdistally around the canister 40 within the first chamber 422 into thesecond chamber 426, similar to other embodiments herein. The O-ring 462a on the proximal plunger plug 462 (and/or other seals, not shown), mayprovide a fluid-tight seal such that the gas pressure applies a distalforce on the proximal surface of the proximal plunger cap 462. As theplunger cap 462, and consequently, the plunger 450, is directeddistally, the annular volume within the second chamber 426 is reduced,thereby forcing the damping fluid 459 to pass through the proximalport(s) 466, the orifice 458, and into the internal chamber 454, andconsequently pushing the internal piston 456 distally, as shown in FIG.7B, given the incompressibility of the damping fluid 459 as it entersthe internal chamber 454. As shown in FIG. 8D, one or more groovechannels or other distal ports 464 (two shown) may be provided in thedistal end 452 b of the plunger 450 such that the distal region of theinternal chamber 454 communicates with the external atmosphere. Thus, asthe internal piston 456 moves distally, air within the internal chamber454 distal to the internal piston 456 may freely escape through theports 464 with minimal resistance.

The resulting flow of the damping fluid may dampen movement of theplunger 450, e.g., to slow advancement and/or dampen abrupt motion,variations due to varying resistance, or other undesired movement, e.g.,to provide a more uniform advancement speed of the plunger 450 and,consequently, flow rate of the agent from the injector module (notshown) coupled to the drive module 410.

The orifice 458 may create a relatively high resistance to the dampingfluid 459 flowing from the second chamber 426 through the proximal port466 into the internal chamber 454, e.g., by restricting flow of thedamping fluid 459. Optionally, it may desirable to modify theadvancement speed of the plunger 450, e.g., by adjusting the size of theorifice 458. In an exemplary embodiment, different orifices havingdesired inner diameters may be provided that may be individuallyinserted into the plunger 450 to provide a desired resistance. Forexample, as best seen in FIG. 8C, the proximal plunger cap 462 mayinclude an opening sealed by a removable plug 462 b. If a different sizeorifice is desired, the plug 462 b may be removed, and a desired orifice458 inserted through the opening and secured within the plunger 450,e.g., press-fitted or otherwise secured within the proximal end 452 a ofthe plunger 450, whereupon the plug 462 b may be used to reseal theopening. Alternatively, the advancement speed of the plunger 450 may bemodified by changing the viscosity of the damping fluid 459.

The plunger configuration shown in FIGS. 7A and 7B may provide oildamping that is “in parallel” with the canister 40 and plunger 450.Alternatively, as shown in FIG. 9A, damping may be provided to a drivemodule 510 “in series” with a canister 40 and plunger 550. Generally,the drive module 510 includes a drive housing 512 including a firstportion 520 containing a puncture mechanism 30 (e.g., similar to thatshown in FIGS. 3A and 3B, although any of the puncture mechanismsdescribed herein may be provided instead) and a canister 40 within afirst chamber 522, and a second portion 524 including a plunger 550slidably disposed within a second chamber 526, similar to otherembodiments herein.

However, in this alternative, an accumulator chamber 554 is providedbetween first and second accumulator pistons 560, 562 with the firstpiston 560 disposed adjacent the first chamber 522 and the second piston562 disposed adjacent the second chamber 526. An orifice 528 may beprovided in the second piston 562 to allow damping fluid 559 within theaccumulator chamber 554 to travel through the orifice 558 into thesecond chamber 526 to advance the plunger 550 distally. For example,when the puncture mechanism 30 is activated to direct puncture pin 534to penetrate the septum 46 of the canister 40, gas may flow distallyaround the canister 40 within the first chamber 522 to generate a distalforce on the first accumulator piston 560, forcing the first piston 560to advance distally within the accumulator chamber 554.

Given the incompressibility of the damping fluid 559, the force causesthe damping fluid 559 to flow through the orifice 558 into the secondchamber 526, thereby advancing the plunger 550 (and a piston of aninjector module, not shown, coupled to the drive module 510 to deliveran agent therein). The size of the orifice 558 and the viscosity of thedamping fluid 559 may be selected to cause the plunger 550 to advance ata desired speed.

One disadvantage of “in series” damping is that it may increase theoverall length of the drive module 510, e.g., compared with “inparallel” damping, e.g., as provided by the drive module 410′ shown inFIG. 9B (which operates generally similar to the drive module 410 shownin FIGS. 7A and 7B, although with a different puncture mechanism 30). Inparallel damping may provide comparable damping within a shorter drivehousing and/or may otherwise allow optimization of the drive modulewithout compromising the diameter of the drive module. For example, inthe embodiments shown in FIGS. 9A and 9B, the drive module 410′ mayprovide the same stroke length of the plunger and output force with thesame outer diameter and a relatively shorter length housing.

Turning to FIGS. 10A and 10B, another exemplary embodiment of agas-powered drive module 610 is shown that may be included in aninjection device, such as any of the embodiments described herein.Generally, the drive module 610 includes a drive housing 612 containinga puncture mechanism 630, a canister 40, and an actuation mechanism 660for directing the canister 40 from an inactive position (FIG. 10A),where a septum 46 of the canister 40 is spaced apart from a puncture pin634 of the puncture mechanism 630, and an inactive position (FIG. 10B),where the canister 40 is advanced distally such that the puncture pin634 penetrates the septum 46, thereby releasing gas within the cavity 48of the canister 40, which may be used to advance a plunger and/or pistonof an injector module (not shown) coupled to the drive module 610.

Generally, the canister 40 includes a main barrel region 42 a, anenclosed base or first end 42 b, a tapered shoulder region 42 c, and anopen neck region or second end 42 d defining an opening or passagewithin which a cap 44 including the septum 46 is welded or otherwiseattached. As shown, the canister 40 may be disposed within the drivehousing 612 with the second end 42 d and cap 44 oriented distallyrelative to the first end 42 b.

The canister 40 may be carried by a canister sleeve 640, e.g., that fitssnugly around the barrel region 42 a and/or first end 42 b of thecanister 40 that is slidably disposed within the drive housing 612. Forexample, the canister sleeve 640 may include an O-ring 642 and/or sealthat slidably engages the inner surface of the drive housing 612 toprovide a fluid-tight seal, thereby defining an enclosed chamber 622within the drive housing 612, e.g., between the O-ring 642 and aproximal wall 614 of the drive housing 612. The chamber 622 may befilled with damping fluid, e.g., a silicone oil and/or otherincompressible, viscous fluid 659.

The puncture mechanism 630 may include a pin piston or bulkhead 632disposed within the drive housing 612 distal to the canister 40, e.g.,including one or more O-rings 633 to provide a fluid-tight seal. Thebulkhead 632 and/or drive housing 612 may include one or morecooperating features 635, e.g., detents, tabs, catches, hem support, andthe like, that prevent axial movement of the bulkhead 632 within thedrive housing 612, e.g., distally away from the canister 40.

The puncture pin 634 may be carried by the bulkhead 632, e.g., centeredand/or otherwise aligned with the longitudinal axis 618 of the drivemodule 610 such that the puncture pin 634 may penetrate the septum 46when the canister 40 is advanced, as described further elsewhere herein.The puncture pin 634 may be a hollow needle or other tubular body thatmay provide a passage for gas from the cavity 48 of the canister 40 topass therethrough distally beyond the bulkhead 632, e.g., to advance aplunger and/or piston of an injector device (not shown).

In addition, the drive module 610 includes an actuator mechanism 660that may manipulated by a user to advance the canister 40 from theinactive position to the active position. As shown, the actuatormechanism 660 generally includes an actuation sleeve 662 slidablydisposed over the drive housing 612 and a activation plunger 664 mountedto the actuation sleeve 662, e.g., to a proximal wall 662 a thereof thatmay be initially provided in a proximal position (FIG. 10A) and manuallyadvanced to a distal position (FIG. 10B).

For example, an activation plunger housing 666 may be mounted within thedrive housing 612, e.g., immediately adjacent the proximal end 614,through which the actuation plunger 664 may be slidably received. In theproximal position, an open space may be provided between the actuationplunger 664 and the first end 42 b of the canister 40 and canistersleeve 640, which may be filled with damping fluid 659, as shown in FIG.10A.

During activation, the actuation sleeve 660 may be advanced distallyrelative to the drive housing 612, thereby directing the actuationplunger 664 distally towards the canister 40, as shown in FIG. 10B.Given the incompressibility of the damping fluid 659, the actuationplunger 664 may apply a force to the damping fluid 659, which may betransferred to the canister sleeve 640, thereby causing the canistersleeve 640 and canister 40 to translate axially, e.g., until thepuncture pin 634 penetrates the septum 46, thereby releasing gas fromthe canister 40. The viscosity of the damping fluid 659 may slow and/orotherwise limit the speed of the advancement of the canister 40 duringactivation. By taking advantage of the area ratio of the actuationplunger 634 and canister sleeve 640, a puncture force sufficient topenetrate the septum 46 may be achieved with minimal effort by the user.

In addition, when the septum 46 is penetrated, the initial outburst ofgas pressure may tend to cause the canister 40 to recoil proximallywithin the drive housing 612, which may also cause the actuation plunger634 and actuation housing 660 to also spring back proximally. To preventsuch recoil, a ratchet mechanism may be provided that may allow thecanister sleeve 640 to advance distally to the active position andprevent subsequent proximal movement. For example, as shown, thecanister sleeve 640 may include one or more ratchet teeth 644 on theouter surface of the sleeve 640 that may interact with one or moreratchet arms 668 extending from the plunger housing 666 and/or the drivehousing 612. For example, a plurality of annular teeth or other ridges644 may be provided that extend around the canister sleeve 640 thatinclude blunt proximal edges and ramped distal edges. the distal edgesmay accommodate distal movement of the canister sleeve 640, with thetips of the ratchet arms 668 sliding over the teeth 644 as the canistersleeve 640 moves distally. However, if the canister sleeve 640 attemptsto move back proximally, e.g., in response to gas pressure from thecanister 40, the tips may engage the blunt proximal edges, therebypreventing proximal movement.

Turning to FIGS. 11A-11B, another exemplary embodiment of anauto-injector device 708 is shown that may perform multiple successiveactions automatically in response to a single actuation action, i.e.,upon release of pressurized gas within a canister 40 within the injectordevice 708. Generally, as shown, the injector device 708 includes anouter housing 712 containing the various components of the injectordevice 708, e.g., including a drive module or portion 710 and aninjector module or portion 760, which may be constructed and/or operategenerally similar to other embodiments herein. Unlike previousembodiments, the components of both the drive module 710 and injectormodule 760 are contained within the same housing 712, i.e., such thatthe components may not be modified once the device 708 is assembled.

Optionally, similar to other embodiments herein, the components of thedrive module 710 and injector module 760 may be provided as separateassemblies (not shown), that may be attached and/or otherwise assembledtogether, e.g., similar to other embodiments herein. In addition oralternatively, although a particular example of a drive module 710 andinjector module 760 are shown, it will be appreciated that the drivemodule 710 may be replaced with a different drive module, e.g., similarto other drive modules described herein, that are modified to allowinstallation within the housing 712. Similarly, the injector module 760may be modified to include a separate, e.g., single-dose, syringe device(not shown) that may be installed within the injector portion 760 orintegral syringe, e.g., also similar to other embodiments herein.

Generally, in the embodiment shown, the drive module 710 includes afirst chamber 722 and a second chamber 726 defined by the housing 712(or an internal cylinder within the housing 712) that are spaced apartaxially from one other and communicate with one another via anintermediate passage 728. The canister 40 and a puncture mechanism 730may be provided within the first chamber 722 and a piston 750 may beprovided within the second chamber 726, e.g., similar to otherembodiments herein.

For example, as best seen in FIG. 11A(1), the canister 40 may include abody 42 and a cap 44 including a septum 46 welded to the body 42 toprovide an enclosed cavity 48 filled with a fluid, similar to theembodiments described herein, that is slidably mounted within the firstchamber 722. In an exemplary embodiment, the canister 40 may be securedwithin a canister sleeve 740 that may be slidable within the firstchamber 722 and/or relative to the housing 712 with the cap 44 orientedproximally towards the puncture mechanism 730.

The puncture mechanism 730 may include a pin sleeve or bulkhead 732slidably disposed at least partially within the first chamber 722, e.g.,immediately adjacent the first end 714 or otherwise proximal to the cap44 of the canister 40. The pin sleeve 732 carries a puncture pin 734 andis movable axially relative to the housing 712, e.g., by manuallyadvancing an external actuation sleeve 736, thereby directing thepuncture mechanism 730 axially between an inactive position wherein thepuncture pin 734 is spaced apart from the septum 46 (e.g., as shown inFIG. 11A) and an active position wherein the puncture pin 734 penetratesthe septum 46 (e.g., as shown in FIG. 11B) to release gas from thecavity 48 of the canister 40, as described elsewhere herein.

The injector module 760 generally includes an injector housing 762defining a substantially enclosed agent chamber 772 that slidablyreceives a piston 776 and includes a needle 778 permanently mounted orremovably attached to a distal end 762 b of the injector housing 762 fordelivering one or more agents within the agent chamber 772, similar toother embodiments herein. A proximal end of the injector housing 762 amay contact and/or otherwise interact with the canister sleeve 740,e.g., such that distal movement of the canister sleeve 740 causescorresponding distal motion of the injector sleeve 762.

In an exemplary embodiment, the injector sleeve 762 may be biased to aninitial or proximal position, e.g., by spring mechanism 782 coupled orotherwise positioned between the distal end 762 b of the injector sleeve762 and the housing 712, e.g., a distal cap 717 carried on the distalend 716. For example, the spring mechanism 782 may be a compressionspring mounted between the distal end 762 b of the injector sleeve 762and the distal cap 717, thereby biasing the injector sleeve 762, andconsequently, the canister sleeve 740, proximally within the housing712. As described further elsewhere herein, the canister sleeve 740 maybe directed distally by overcoming this bias, thereby also directing theinjector sleeve 762 distally to compress or otherwise increase potentialenergy in the spring 782. The distal cap 717 may include a distalsurface 717 a, e.g., a substantially flat surface that may be placedagainst a patient's skin or other target injection site (not shown),that includes an opening 717 b through which the needle 778 may bedirected during an injection, as described elsewhere herein.

The plunger 750 may be an elongate rod or other member slidably disposedwithin the second chamber 726 including a proximal end 752 disposedadjacent the intermediate passage 728 and a distal end 754 coupled tothe piston 776 within the agent chamber 772, e.g., similar to otherembodiments herein. Thus, the plunger 750 may be movable from an initialposition (e.g., shown in FIG. 11A) to an extended position (e.g., shownin FIG. 11B) wherein the distal end 754 directs the piston 76 distallyto deliver the agents within the agent chamber 772, as described furtherelsewhere herein.

During use, the device 708 may be initially provided with the puncturemechanism 730 spaced apart from the cap 44 of the canister 40 and withthe injector sleeve 762 and canister sleeve 740 held in the proximalposition by the spring 782, e.g., as shown in FIG. 11A. To perform aninjection, the distal surface 717 a of the distal cap 717 may be placedagainst a patient's skin or other target injection site (not shown), andthe actuation sleeve 736 may be pressed or otherwise directed distally,as shown in FIG. 11B, sufficient distance to cause the puncture pin 734to penetrate the septum 46 of the canister 40 and release gas therein.Initially, release of the gas may cause the canister sleeve 740, andconsequently, the injector sleeve 762, to slide distally, therebydirecting the canister 40 distally away from the puncture pin 734, asshown in FIG. 11C as the proximal region of the first chamber 722 isfilled with the gas. For example, the surface area of the pin sleeve 732within the first chamber 722 may result in a translational force that isgreater than the resistance of the spring 782 to compression. Inaddition, as the gas travels distally around the canister 40 within thefirst chamber 722, the resistance of the plunger 750 to movement and/orthe surface area of the proximal end 752 may result in an initial forcetranslating the canister sleeve 740 and injector sleeve 762 distally, asshown in FIG. 11C. This translation causes the needle 778 to passthrough the opening 717 b in the distal cap 717, thereby penetrating thepatient's skin.

Once the canister sleeve 740 and injector sleeve 762 have moved to thedistal position, further gas pressure from the canister 40 may then acton the proximal end 752 of the plunger 750, thereby directing theplunger 750, and consequently the piston 776, distally to deliver theagent within the agent chamber 762 through the needle 778 into thepatient's body, as shown in FIG. 11D. Sufficient gas may be providedwithin the canister 40 to fully advance the plunger 750 and piston 776to deliver the entire contents of the agent chamber 772. For example, asdescribed elsewhere herein, as long as a portion of liquefied gasremains within the canister 40, the pressure applied to the plunger 750will be substantially constant to provide substantially uniformadvancement of the piston 776 to deliver the agent. However, thecanister 40 may include any single-phase or dual-phase fluid, such asthose described elsewhere herein.

Optionally, as shown in FIG. 11E, a vent 756 (shown in phantom) may beprovided in the housing 712 (or cylinder defining the second chamber726) and the injector housing 762 that communicates with the secondchamber 726 at a location such that, when the proximal end 752 of theplunger 750 passes the vent, the second chamber 726 may communicate withthe external environment through the vent 756. Thus, this creates afluid communicating back to the first chamber 722 and the cavity of thecanister 40, allowing all remaining gas to be vented, e.g., until thepressure within the device 708 achieves atmospheric pressure. As aresult of this venting, the potential energy stored in the spring 782may overcome the residual has pressure, and direct the injector housing762 and canister sleeve 740 back towards the initial position, therebywithdrawing the needle 778 from the patient back through the opening 717b in the distal cap 717. With the needle 778 withdrawn and guarded, thedevice 708 may be safely disposed of.

It will be appreciated that elements or components shown with anyembodiment herein are exemplary for the specific embodiment and may beused on or in combination with other embodiments disclosed herein.

While the invention is susceptible to various modifications, andalternative forms, specific examples thereof have been shown in thedrawings and are herein described in detail. It should be understood,however, that the invention is not to be limited to the particular formsor methods disclosed, but to the contrary, the invention is to cover allmodifications, equivalents and alternatives falling within the scope ofthe appended claims.

1. A device for delivering one or more agents into a patient's body,comprising: a) a drive module comprising: an elongate drive housingincluding a first end and a second end, a first chamber adjacent thefirst end communicating with a second chamber adjacent the second endvia an intermediate passage; a puncture mechanism within the firstchamber adjacent the first end including a puncture pin; a canistercontaining pressurized gas including a penetrable septum disposedadjacent the puncture pin; an actuator configured to move one of thepuncture mechanism and the canister to cause the puncture pin topenetrate the septum and cause the gas within the canister to flowthrough the first chamber around the canister, through the intermediatepassage, and into the second chamber; and a plunger slidably disposedwithin the second chamber such that gas entering the second chambercauses the plunger to move from an initial position to an extendedposition wherein a distal end of the plunger extends from the second endof the drive housing; and b) an injector module comprising: an injectorhousing coupled to the drive housing carrying an agent chambercontaining one or more agents; a piston slidably disposed within theagent chamber and coupled to the distal end of the plunger; and a needleextending from the injector module opposite the drive housing andcommunicating with the agent chamber for delivering the one or moreagents from the agent chamber when the plunger moves from the retractedposition to the extended position, thereby advancing the piston withinthe agent chamber.
 2. The device of claim 1, wherein the injectorfurther comprises a needle guard movable from a guarded position whereinthe needle guard covers the needle and a retracted position wherein theneedle is exposed to perform an injection, the needle guard coupled tothe actuator and slidable along the drive housing such that the needleguard activates the actuator when directed to the retracted position. 3.The device of claim 2, wherein the needle guard is biased to the guardedposition.
 4. The device of claim 3, further comprising: an actuationsleeve slidably disposed over the drive housing and coupled to theneedle guard; and a spring coupled between the actuation sleeve anddrive housing to bias the needle guard to the guarded position.
 5. Thedevice of claim 4, wherein the puncture mechanism comprises a pin sleeveslidably disposed within the first chamber adjacent the first end andcarrying the puncture pin, the pin sleeve movable from an inactiveposition wherein the puncture pin is spaced apart from the septum and anactive position wherein the puncture pin penetrates the septum, the pinsleeve biased to the active position and restrained in the inactiveposition by the actuator.
 6. The device of claim 5, wherein the actuatorcomprises one or more catches on the drive housing restraining the pinsleeve in the inactive position, the actuation sleeve configured todisengage the one or more catches to allow the pin sleeve toautomatically move from the inactive position to the active position. 7.The device of claim 6, wherein the actuation sleeve comprises a proximalend initially disposed distal to the one or more catches, the proximalend comprises one or more features for slidably engaging the one or morecatches when the needle guard and actuation sleeve are directedproximally to release the one or more catches.
 8. The device of claim 2,further comprising a locking mechanism for preventing proximal movementof the needle guard from the guarded position until the lockingmechanism is released. 9-10. (canceled)
 11. The device of claim 1,wherein the puncture mechanism comprises a sleeve slidably disposedwithin the first chamber adjacent the first end and carrying thepuncture pin, the sleeve movable from an inactive position wherein thepuncture pin is spaced apart from the septum and an active positionwherein the puncture pin penetrates the septum, the sleeve biased to theactive position and restrained in the inactive position by the actuator.12. The device of claim 1, wherein the injector module further comprisesa syringe mounted within the injector housing comprising a barreldefining the agent chamber, and wherein the needle extends from a distalend of the syringe and the piston is slidable within the barrel. 13-19.(canceled)
 20. The device of claim 1, wherein the puncture mechanismcomprises a pin holder slidably disposed within the first chamberadjacent the first end and carrying the puncture pin, the pin holdermovable from an inactive position wherein the puncture pin is spacedapart from the septum and an active position wherein the puncture pinpenetrates the septum, the actuator coupled to the pin holder to movethe pin holder from the inactive position to the active position. 21.The device of claim 20, wherein the pin holder comprises a lead screwcomprising threads that cooperate with the first end of the drivehousing such that rotation of the lead screw causes the lead screw tomove from the inactive position to the active position.
 22. The deviceof claim 21, further comprising a rotating handle mounted on the firstend of the drive housing and coupled to the lead screw, the handlerotatable relative to the drive housing for directing the lead screwfrom the inactive position to the active position.
 23. The device ofclaim 21, wherein the actuator comprises a handle pivotally coupled tothe drive housing and a linking bar coupled between the handle and thepin holder such that rotation of the handle about a pivot to cause thelinking bar to direct the pin holder from the inactive position to theactive position.
 24. The device of claim 20, wherein the actuatorcomprises an actuation button extending from the drive housing andcoupled to the pin holder, the actuation button advanceable to directthe pin holder distally for sufficient distance to move the pin holderfrom the inactive position to the active position.
 25. (canceled) 26.The device of claim 1, wherein the septum of the canister is orienteddistally within the first chamber, and the puncture mechanism isdisposed distal to the canister within the first chamber such that thepuncture pin is oriented proximally towards the septum. 27-31.(canceled)
 32. The device of claim 1, wherein the plunger comprises: anelongate tubular member comprising a proximal end and a distal anddefining an internal chamber extending between the proximal end and thedistal end; a proximal plunger cap on the proximal end of the tubularmember for slidably engaging a wall of the drive housing surrounding thesecond chamber to isolate an annular region of the second chambersurrounding the tubular member distal to the plunger cap; an orificecarried on a proximal end of the tubular member communicating betweenthe annular region and the internal chamber; an internal piston withinthe internal chamber immediately adjacent the orifice; and damping fluidwithin the annular region, wherein distal movement of the plunger fromthe initial position to the extended position causes a volume of theannular region to decrease, thereby directing the damping fluid from theannular region through the orifice into the internal chamber proximal tothe internal piston, thereby directing the internal piston distally anddamping the movement of the plunger. 33-44. (canceled)
 45. A drivemodule for an injection device for delivering one or more agents into apatient's body, comprising: an elongate drive housing including a firstend and a second end, a first chamber adjacent the first endcommunicating with a second chamber adjacent the second end via anintermediate passage; a puncture mechanism comprising a pin holderwithin the first chamber immediately adjacent the first end including apuncture pin; a canister containing pressurized gas including apenetrable septum disposed adjacent the puncture pin, the pin holdermovable distally from an inactive position wherein the puncture pin isspaced away from the septum and an active position wherein the puncturepin penetrates the septum and causes the gas within the canister to flowthrough the first chamber around the canister, through the intermediatepassage, and into the second chamber; a plunger slidably disposed withinthe second chamber such that gas entering the second chamber causes theplunger to move from an initial position to an extended position whereina distal end of the plunger extends from the second end of the drivehousing for delivering one or more agents from an injector module basedon movement of the plunger; and an actuator for directing the pin holderfrom the inactive position to active position. 46-54. (canceled)
 55. Amethod for assembling an injector device, comprising: a) providing adrive module comprising: a drive housing including a first end and asecond end, a first chamber adjacent the first end communicating with asecond chamber adjacent the second end via an intermediate passage; apuncture mechanism comprising a pin holder within the first chamberimmediately adjacent the first end including a puncture pin; a canistercontaining pressurized gas including a penetrable septum disposedadjacent the puncture pin, the pin holder movable distally from aninactive position wherein the puncture pin is spaced away from theseptum and an active position wherein the puncture pin penetrates theseptum and causes the gas within the canister to flow through the firstchamber around the canister, through the intermediate passage, and intothe second chamber; a plunger slidably disposed within the secondchamber such that gas entering the second chamber causes the plunger tomove from an initial position to an extended position wherein a distalend of the plunger extends from the second end of the drive housing fordelivering one or more agents from an injector module based on movementof the plunger; and an actuator for directing the pin holder from theinactive position to active position; b) providing an injector modulecomprising an injector housing carrying an agent chamber containing oneor more agents and a piston slidably disposed within the agent chamberin a proximal position; and c) coupling the injector housing to thesecond end of the drive housing, thereby coupling the plunger to thepiston such when the plunger moves from the retracted position to theextended position, the piston is advanced within the agent chamber todeliver the one or more agents from the agent chamber. 56-60. (canceled)61. A method for performing an injection, comprising: a) providing aninjection device comprising: a drive module including a canistercontaining pressurized gas within a first chamber and a plunger within asecond chamber communicating with the first chamber, and; an injectormodule including one or more agents within an agent chamber, a pistonwithin the agent chamber coupled to the plunger, a needle; and a needleguard covering the needle; b) pressing the needle guard against apatient's skin, thereby causing the needle guard to retract andinserting the needle into the patient's skin; and c) wherein retractionof the needle guard activates an actuator to cause a puncture pin withinthe drive module to penetrate a septum of the canister thereby causinggas within the canister to flow through the first chamber around thecanister and into the second chamber, thereby moving the plunger from aninitial position to an extended position and, consequently, advancingthe piston within the agent chamber to deliver the one or more agentsthrough the needle into the patient's body. 62-64. (canceled)